MacPorts: MySQL upgrade from 5.0.x to 5.1.x gives error during insert ( mysql_upgrade / ERROR 1558 (HY000) ) 3

Yesterday I upgraded my mysql from 5.0.x to 5.1.x. After upgrade inserts started to fail with this error: ERROR 1558 (HY000) at line 146: Column count of mysql.proc is wrong. Expected 20, found 16. Created with MySQL 50067, now running 50142. Please use mysql_upgrade to fix this error. After little bit of google I found ...